Digital rights management (DRM) enables the delivery of content from a source to a recipient, subject to restrictions defined by the source concerning use of the content. Exemplary DRM systems and control techniques are described in U.S. Pat. No. 7,073,199, issued Jul. 4, 2006, to Raley, and U.S. Pat. No. 6,233,684, issued May 15, 2001, to Stefik et al., which are both hereby incorporated by reference in their entireties. Various DRM systems or control techniques (such as those described therein) may be used with the obscuration techniques described herein.
One of the biggest challenges with controlling access and use of content is to prevent users from accessing the content in a manner other than those permitted by usage rights. As known in the art, usage rights indicate how content may be accessed or otherwise used. Usage rights may be embodied in any data file and/or defined using program code, and may further be associated with conditions that must be satisfied before access or other use of the content is permitted. Usage rights, which are also referred to as “usage rules” herein, may be supported by cohesive enforcement units, which are trusted devices that maintain one or more of physical, communications and behavioral integrity within a computing system.
For example, if the recipient is allowed to create an unauthorized (not DRM-protected) copy of the content, then the recipient's use of the copy would not be subject to any use restrictions that had been placed on the original content. When DRM systems impose restrictions on the use of a rendering device, for example, by preventing or impeding the use of the screen capture features, a conflict arises between the rendering device owner's (user, receiver, or recipient) interest in being able to operate their device with all of its features without restriction (including screen capture capability), and the content provider's (sender, or source) interest in regulating and preventing copying of the content rendered on the recipient's devices. This conflict has historically been overcome by establishing trust between the content supplier and the rendering device. By establishing trust in this manner, the content supplier can ensure that the rendering device will not bypass DRM restrictions on rendered content.
There is a field of technology devoted to trusted computing which balances control of the rendering device by the content provider with control by the recipient. In cases where the recipient operates a trusted client and the content provider (source) controls the trusted elements of the client, screen capture by the device (e.g., satellite DVRs, game consoles and the like) can be prevented by disabling those capabilities. However, users typically operate devices that are substantially under their control (e.g., PCs, Macs, mobile phones and the like), such that installation and execution of software may be initiated and/or controlled by a user.
U.S. Pat. No. 8,914,906 discloses a method and apparatus for identifying whether a rendering engine is secure and if not, for obtaining the requisite security components to render protected content.